Can ng-show directive be used with a delay - angularjs

Question

I have a spinner this is shown with ng-show="loading>0"
Is there a way I can display this spinner with a delay (say 1 second)?
I can't use a timeout because with multiple requests de loading counter will get out of sync.
What I need is a delay on the ng-show via css transition or similar

Answer 1

My suspicion is that you are looking for a general purpose spinner that includes a delay. The standard, show after 200ms or something like that.
This is a perfect candidate for a directive, and actually pretty easy to accomplish.
I know this is a long code example, but the primary piece is the directive. It's pretty simple.
Listen to a few scope variables and shows after some configurable delay. If the operation takes longer than the delay, it will just get canceled and never show up.
(function() {
'use strict';
function SpinnerDirective($timeout) {
return {
restrict: 'E',
template: '<i class="fa fa-cog fa-spin"></i>',
scope: {
show: '=',
delay: '#'
},
link: function(scope, elem, attrs) {
var showTimer;
//This is where all the magic happens!
// Whenever the scope variable updates we simply
// show if it evaluates to 'true' and hide if 'false'
scope.$watch('show', function(newVal){
newVal ? showSpinner() : hideSpinner();
});
function showSpinner() {
//If showing is already in progress just wait
if (showTimer) return;
//Set up a timeout based on our configured delay to show
// the element (our spinner)
showTimer = $timeout(showElement.bind(this, true), getDelay());
}
function hideSpinner() {
//This is important. If the timer is in progress
// we need to cancel it to ensure everything stays
// in sync.
if (showTimer) {
$timeout.cancel(showTimer);
}
showTimer = null;
showElement(false);
}
function showElement(show) {
show ? elem.css({display:''}) : elem.css({display:'none'});
}
function getDelay() {
var delay = parseInt(scope.delay);
return angular.isNumber(delay) ? delay : 200;
}
}
};
}
function FakeService($timeout) {
var svc = this,
numCalls = 0;
svc.fakeCall = function(delay) {
numCalls += 1;
return $timeout(function() {
return {
callNumber: numCalls
};
}, delay || 50);
};
}
function MainCtrl(fakeService) {
var vm = this;
vm.makeCall = function(delay) {
vm.isBusy = true;
fakeService.fakeCall(delay)
.then(function(result) {
vm.result = result;
}).finally(function() {
vm.isBusy = false;
});
}
}
angular.module('spinner', [])
.service('fakeService', FakeService)
.controller('mainCtrl', MainCtrl)
.directive('spinner', SpinnerDirective);
}());
<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.1/css/bootstrap.min.css" rel="stylesheet" />
<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css" rel="stylesheet">
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.8/angular.min.js"></script>
<div class="container" ng-app="spinner">
<div class="row" ng-controller="mainCtrl as ctrl">
<div class="col-sm-12">
<h2>{{ctrl.result | json}}
<spinner show="ctrl.isBusy" delay="200"></spinner>
</h2>
<button type="button"
class="btn btn-primary"
ng-click="ctrl.makeCall(2000)"
ng-disabled="ctrl.isBusy">Slow Call
</button>
<button type="button"
class="btn btn-default"
ng-click="ctrl.makeCall()"
ng-disabled="ctrl.isBusy">Fast Call
</button>
</div>
</div>
</div>

Answer 2

Here's a simpler approach that worked for my needs. Depending on what your action is, you would tie function setDelay() to the element. For example, in my case I tied setDelay() to a select input.
Trigger HTML:
<select class="first-option"
ng-change="setDelay()"
ng-options="o.label for o in download.options"
ng-model="optionModel" required>
</select>
In your controller, add a simple function setDelay that will change the flag $scope.delay:
$scope.setDelay = function(){
$scope.delay = true;
$timeout(function(){
$scope.delay = false;
}, 200);
};
Then, you can simply use $scope.delay as a flag in ng-show:
<div class="loading-div" ng-show="delay">
<img src="loading_spinner.gif">
</div>
And show content after done loading:
<div ng-show="!delay">
Content is loaded.
</div>
Now, every time the user selects a new value in the dropdown menu, it will trigger$scope.delay to be set totrue causing the spinner to show, and when it reaches 200, it will be set to false causing the spinner to hide.

Answer 3

I think a pure CSS solution is the best way to do it.
Here is a plunker showing how to do it. Using ng-animate classes for transition and applying a transition delay with a transition of 10ms (0s transition is not working with css).
Relevant part of the code :
.your-element-class.ng-hide {
opacity: 0;
}
.your-element-class.ng-hide-add,
.your-element-class.ng-hide-remove {
transition: all linear 0.01s 1s;
}
The only reason to use a custom directive for it would be using this tons of times in your code with different delays value. A custom directive allow more flexibility with the delay timing.